Terminal assemblies including electrical terminals and electrical wires connected to the electrical terminals are used in plug connectors and cable trees. The cable trees and the terminals in plug connectors are often produced from copper or a copper alloy. However, copper is very heavy and is relatively expensive. Cable trees and plug connectors are increasingly being miniaturized, in the automotive industry for example, to save weight and cost. Alternative conductor materials which are lighter and cheaper than copper are therefore increasingly considered; conductors made from base metals—metals which, in the electrochemical series, have a standard electrode potential smaller than the standard electrode potential of hydrogen—are lighter and cheaper than copper. The base metal may be, for example, aluminum or an aluminum alloy.
However, when connecting conductors which comprise a base metal to a terminal which comprises copper or another noble metal, it is difficult to produce a reliable mechanical and electrical connection between the conductor and the terminals. A mechanical connection of a conductor and a terminal which are composed of different metals or metal alloys is problematic as the connection is relatively weak and plug connectors in the automotive sector, for example, are exposed to large physical stresses and must therefore withstand high forces. Further, the connection of a terminal which comprises copper or a more noble metal to a conductor which comprises a base metal such as aluminum, for example, is electrochemically problematic because the point of contact between the noble and less noble metals is in danger of corroding. Due to the differing dissolution potentials of the different metals, galvanic corrosion can occur if the connection area comes into contact with an electrolyte, water, or moisture. The less noble metal becomes the anode and the more noble metal becomes the cathode, which leads to the dissolution of the anode. Such a corrosion thus weakens the mechanical connection. The corrosion may also impair the charge transfer if an oxidation layer is formed in the event of corrosion.
To prevent corrosion between the different materials of the terminal and the conductor, it is common to use a lubricant or a holt-melt adhesive to create a fluid-tight seal around the connection area. Lubricants, however, must be applied before the terminal is mechanically and electrically conductively connected to the conductor in the connection area, which negatively affects the mechanical stability of the connection. The same applies to the use of hot-melt adhesives as sealing materials. Sealing after the conductor and the terminal are already mechanically and electrically conductively connected to one another is complex and difficult to accomplish because the connection area can only be accessed with difficulty after connection, for example when it is inside a crimping sleeve. Conversely, the use of special seals is generally expensive and requires complex structural changes to the components of a terminal assembly in order to provide the seals with suitable sealing sites.